The disclosure relates to image retrieval and, more specifically, to medical image retrieval of an image having high similarity to an acquired image from among a plurality of stored images.
In medical practice, it is important to recognize the internal states of a patient on the basis of images acquired by radiography. An X-ray image of a patient can be compared with X-ray images taken in the past to identify the causes of symptoms of the patient. This enables selection of appropriate medical treatment, leading to early improvement of the symptoms of the patient.
Japanese Unexamined Patent Publication No. 2005-237781 discloses a cardiomagnetometer which measures a cardiac magnetic signal and compares the measured cardiac magnetic signal with those measured in the past to determine whether the person is suffering from a cardiac disease or whether he/she is a candidate thereof. Japanese Unexamined Patent Publication No. 2008-077163 discloses a search system that calculates a similarity between a latest diagnosis image and each of diagnosis images included in past interpretation report data and, in consideration together with the rate of occurrence of a diagnosis result name in the past interpretation report data, searches for a past diagnosis image and the interpretation report data corresponding thereto.
In Japanese Unexamined Patent Publication No. 2005-237781, the determination is made on the basis of a cardiac magnetic signal, which is indirect information, and therefore an occurrence of a cardiac disease cannot be distinguished from an occurrence of any other disease indicated by a similar signal. In Japanese Unexamined Patent Publication No. 2008-077163, although the similarity between images is calculated by using a Euclidean distance between feature parts in the images, it is necessary to determine which part of the picked-up image is the feature part and, as such, the determination might depend on a doctor's skill in image reading.